首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   62872篇
  免费   3154篇
  国内免费   52篇
  2020年   622篇
  2019年   778篇
  2018年   1075篇
  2017年   1111篇
  2016年   1164篇
  2015年   856篇
  2014年   999篇
  2013年   4660篇
  2012年   1889篇
  2011年   2037篇
  2010年   1324篇
  2009年   1378篇
  2008年   1819篇
  2007年   1864篇
  2006年   1640篇
  2005年   1469篇
  2004年   1370篇
  2003年   1283篇
  2002年   1368篇
  2001年   2097篇
  2000年   2013篇
  1999年   1553篇
  1998年   746篇
  1997年   656篇
  1996年   683篇
  1995年   595篇
  1993年   606篇
  1992年   1307篇
  1991年   1211篇
  1990年   1201篇
  1989年   1102篇
  1988年   1064篇
  1987年   1022篇
  1986年   1081篇
  1985年   1081篇
  1984年   914篇
  1983年   817篇
  1982年   586篇
  1979年   962篇
  1978年   680篇
  1975年   781篇
  1974年   846篇
  1973年   946篇
  1972年   810篇
  1971年   768篇
  1970年   678篇
  1969年   695篇
  1968年   902篇
  1967年   809篇
  1966年   699篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
72.
73.
74.
75.
Public goods theories highlight an incentive system that rewards ‘free riding’ on the contributions of early contributors toward collective actions. However, because such theories focus on creation of the good, they may underestimate returns that accrue to early contributors subsequent to the good's realization. The concept of formative investment is introduced here to describe the extent to which organizations help to create public goods such as interorganizational linkages like participatory federations. Data from the CEOs of 48 organizations involved in a participatory federation were used to assess how an organization's level of formative investment is related to later patterns of dependency and interaction among federation members. Findings suggest that from a long‐term perspective, and for goods that involve communication and interaction, the incentive structure may not be so favorable for free riders. To the extent that organizations with high formative investment have the capability to envision the future and communicate that vision to potential federation partners, they may be able to both reduce free riding and secure for themselves advantageous positions in the subsequent network of relations.  相似文献   
76.
In Experiment 1, rats were trained on a discrimination between rubber- and sandpaper-covered arms of a maze after one group had been pre-exposed to these intra-maze cues. Pre-exposure facilitated subsequent discrimination learning, unless the discrimination was made easier by adding further discriminative stimuli, when it now significantly retarded learning. In Experiment 2, rats were trained on an extra-maze spatial discrimination, again after one group, but not another, had been pre-exposed to the extra-maze landmarks. Here too, pre-exposure facilitated subsequent discrimination learning, unless the discrimination was made substantially easier by arranging that the two arms between which rats had to choose were always separated by 135°. The results of both experiments can be explained by supposing that perceptual learning depends on the presence of features common to S+ and S-.  相似文献   
77.
78.
79.
The token economy has been the primary model for the behavioral management of inpatient populations. However, this basically operant approach seldom emphasizes the development of cognitive-coping skills to help patients more effectively manage stressors that result in hospitalization. The Therapeutic Contract Program (TCP) is described as an inpatient-treatment strategy that is designed to help foster such cognitive-coping and self-control skills. While external structure is provided by components of this program, subprograms of the TCP have as their goal the development of internally-attributed coping skills and self-perceptions of competence. This preliminary report describes the structure of the TCP, as well as planned and in-progress measures of program participation and treatment outcome.  相似文献   
80.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号